Experimental studies on conscious rabbits are being undertaken to elucidate the response and mechanism of the change in intraocular pressure induced by adrenergic agonists, blocking agents and modulators. Specific areas of immediate investigation include: (1) identification of the peripheral and central actions of the beta adrenoceptor blocking agents, Timolol and Atenolol on intraocular pressure; (2) characterization of the adrenergic supersensitivity in the ocular tissues induced by antimicrotubular drugs, colchicine and vinblastine; (3) measurement of the ocular blood flow changes associated with the peripheral and central actions of clonidine; and (4) correlation of the pulse pressure relationship of the eye with blood measured by the radioactive isotope microsphere technique.